The present invention relates to an automatic machine with a cordless controlled operating wheel.
The present invention may be used to advantage, among other things, on automatic cigarette manufacturing machines, such as filter assembly machines and packaging machines in general comprising at least one operating wheel having a number of individually controlled work stations.
For the sake of simplicity, and purely by way of example, reference is made in the following description to overwrapping machines comprising an operating wheel defined by a heat-seal wheel along which are distributed a number of heat-seal stations.
On known automatic machines for overwrapping packets of cigarettes, e.g. on machines of the type described in Patent Application EP-A-792803, each packet of cigarettes is paired with a respective sheet of plastic heat-seal wrapping material, which is first folded about the packet, and then stabilized by heat sealing to form a tubular wrapping. The open end portions of the tubular wrapping are then folded onto the end walls of the packet, which is fed to a heat-seal wheel on which a respective pair of heat-seal devices engages the end walls of the packet to stabilize the wrapping by heat sealing.
A fairly fast, good-quality heat seal calls for fast, highly accurate temperature control of the heat-seal devices, which, on known automatic machines for overwrapping packets of cigarettes, is performed by a control device carried by the machine in a fixed position off the heat-seal wheel, and which communicates with the heat-seal devices by means of sliding contacts on the heat-seal wheel.
Sliding contacts, however, involve several drawbacks in terms of cost, size and reliability. That is, a heat-seal wheel normally supports from eight to twenty heat-seal devices, each of which requires two signal contacts and two power contacts. Sliding signal contacts are particularly problematic by generating numerous noise signals, and by requiring highly precise mechanical connections and the use of noble materials (gold or silver) to ensure optimum signal transmission and reliability of the contact itself.
It is an object of the present invention to provide an automatic machine with an operating wheel, designed to eliminate the aforementioned drawbacks, and which, in particular, is straightforward and cheap to produce.
According to the present invention, there is provided an automatic machine comprising a fixed central control unit; at least one operating wheel rotating about a central axis and supporting a number of work stations; and a communication apparatus for connecting each said work station to said central control unit; the machine being characterized in that said communication apparatus comprises a cordless communication unit having a movable communication device carried by said wheel, and a fixed communication device carried by the machine; said communication devices being substantially coaxial with said central axis so as to substantially face each other at all times as the wheel rotates.